The present invention relates to an apparatus and a method for determining the particle size and/or particle shape of a mixture of particles according to the preamble of claim 1 as well as to a method of determining the particle size and/or particle shape of a mixture of particles according to the preamble of claim 8.
Such a method and such an apparatus for determining the particle size and/or particle shape of a mixture of particles are known from DE 198 02 141 C1. In such an apparatus, at least two cameras having different magnification factors are provided for recording in order to increase the dynamic range of measurement (the range of the measurable particle sizes). However, it has turned out that the dynamic range of measurement cannot be increased indefinitely even by providing several cameras. In particular, it is difficult to push the lower limit (i.e., the smallest still measurable particle size) further down.
In view thereof, it is an object of the invention to improve an apparatus of the above-mentioned type such that the dynamic range of measurement can be improved. In particular, it is intended to move the lower limit for measurement of still smaller particles. Further, a corresponding method for determining the particle size and/or particle shape of a mixture of particles is to be provided.